List of countries by tax revenue to GDP ratio
en.wikipedia.org
en.wikipedia.org
Capitalist governments are generally captured by capital owners such as in the US. Why would capital owners tax themselves? They want money!
Middle class/working class are not capital owners, even I'd they have an investment account that makes them feel like it
Consolidation of capital and property in the hands of a few is the natural state of capitalism, it's been a slight improvement over the consolidation of feudalism.